#!/usr/bin/env node

/**
 * Git COMMIT-MSG hook for validating commit message
 * See https://docs.google.com/document/d/1rk04jEuGfk9kYzfqCuOlPTSJw3hEDZJTBN5E5f1SALo/edit
 *
 * Installation:
 * >> cd <ocLazyLoad-repo>
 * >> ln -s ../../validate-commit-msg.js .git/hooks/commit-msg
 */
var fs = require('fs');
var util = require('util');


var MAX_LENGTH = 100;
var PATTERN = /^(?:fixup!\s*)?(\w*)(\(([\w\$\.\-\*/]*)\))?\: (.*)$/;
var IGNORED = /^WIP\:/;
var TYPES = {
	feat: true,
	fix: true,
	docs: true,
	style: true,
	refactor: true,
	perf: true,
	test: true,
	chore: true,
	revert: true
};


var error = function() {
	// gitx does not display it
	// http://gitx.lighthouseapp.com/projects/17830/tickets/294-feature-display-hook-error-message-when-hook-fails
	// https://groups.google.com/group/gitx/browse_thread/thread/a03bcab60844b812
	console.error('INVALID COMMIT MSG: ' + util.format.apply(null, arguments));
};


var validateMessage = function(message) {
	var isValid = true;

	if (IGNORED.test(message)) {
		console.log('Commit message validation ignored.');
		return true;
	}

	if (message.length > MAX_LENGTH) {
		error('is longer than %d characters !', MAX_LENGTH);
		isValid = false;
	}

	var match = PATTERN.exec(message);

	if (!match) {
		error('does not match "<type>(<scope>): <subject>" ! was: ' + message);
		return false;
	}

	var type = match[1];
	var scope = match[3];
	var subject = match[4];

	if (!TYPES.hasOwnProperty(type)) {
		error('"%s" is not allowed type !', type);
		return false;
	}

	// Some more ideas, do want anything like this ?
	// - allow only specific scopes (eg. fix(docs) should not be allowed ?
	// - auto correct the type to lower case ?
	// - auto correct first letter of the subject to lower case ?
	// - auto add empty line after subject ?
	// - auto remove empty () ?
	// - auto correct typos in type ?
	// - store incorrect messages, so that we can learn

	return isValid;
};


var firstLineFromBuffer = function(buffer) {
	return buffer.toString().split('\n').shift();
};



// publish for testing
exports.validateMessage = validateMessage;

// hacky start if not run by jasmine :-D
if (process.argv.join('').indexOf('jasmine-node') === -1) {
	var commitMsgFile = process.argv[2];
	var incorrectLogFile = commitMsgFile.replace('COMMIT_EDITMSG', 'logs/incorrect-commit-msgs');

	fs.readFile(commitMsgFile, function(err, buffer) {
		var msg = firstLineFromBuffer(buffer);

		if (!validateMessage(msg)) {
			fs.appendFile(incorrectLogFile, msg + '\n', function() {
				process.exit(1);
			});
		} else {
			process.exit(0);
		}
	});
}
